Families, variants and spawning

Put the shared physics on one parent and only put the differences on the children:

Level	What goes there
Conversion parent	Flight (topology, mass, ground, aero, controls), network, damage mapping, core presentation
Equipment children	Weapon stations, equipment mass and drag, alternate animation graphs, catalog labels
Cosmetic leaves	Liveries and display names

The Huey family is set up this way if you want to look at a working example:

vanilla UH1H_base
  RFM_UH1H_base                      (all flight settings)
    RFM_UH1H
      RFM_UH1H_armed                 (door-gun stations 0/1)
        RFM_UH1H_armed_sharkNose
        RFM_UH1H_armed_gunship_empty (mounts 2/3)
          RFM_UH1H_armed_gunship_HE / _HEDP (+ loaded pods 4/5) and sharkNose variants
    RFM_UH1H_civ_base

A few things that'll catch you out:

• Arrays. When you override an inherited station or animation object, keep its object ID. After saving, check the effective array in Workbench. A loaded gunship should show six stations. Only use the + append syntax where the array expects it (like the faction catalog m_aMultiLists +).
• Spawn registration. Add your variants to Configs/Editor/PlaceableEntities/Vehicles/RFM_Vehicles.conf and to the inline copy in Prefabs/Editor/Modes/EditorModeEdit.et. Use the large vehicle category, and give each variant its own name and faction and helicopter labels.
• Compatibility addons. If you're converting someone else's aircraft, keep your RFM child in your own addon and reference their models and anything you didn't change straight from their mod. Every time they update, re-check the slot names, hit zones, animation object IDs, and that NwkHeliMovementComponent is still off.